资源释放问题

下面是一段ftp下载的代码，下载完后的文件依然被进程占用，我想移动这个文件，一直提示，这个文件被占用！
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;
using System.IO;namespace Update
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        public static string FileName = System.Windows.Forms.Application.StartupPath + "\\System\\Sys.ini";
        public static string downpath = System.Windows.Forms.Application.StartupPath + "\\temp";
        [System.Runtime.InteropServices.DllImport("kernel32")]
        public static extern long WritePrivateProfileString(string section, string key,
                                                             string val, string filePath);        /*参数说明：section：INI文件中的段落；key：INI文件中的关键字；val：INI文件中关键字的数值；
          filePath：INI文件的完整的路径和名称。*/        [System.Runtime.InteropServices.DllImport("kernel32")]
        public static extern int GetPrivateProfileString(string section, string key, string def,
                                                           StringBuilder retVal, int size, string filePath);        /*参数说明：section：INI文件中的段落名称；key：INI文件中的关键字；def：无法读取时候时候的缺省
          数值；retVal：读取数值；size：数值的大小；filePath：INI文件的完整路径和名称。*/
        int UDTimes = 0;
        //
        private void button1_Click(object sender, EventArgs e)
        {
            if (label2.Text == label4.Text)
            {
                MessageBox.Show("已经是最新版本!","提示",MessageBoxButtons.OK,MessageBoxIcon.Asterisk);
            }
            else 
            {
                progressBar1.Visible = true;
                Down();
                StringBuilder temp2 = new StringBuilder(255);
                GetPrivateProfileString("version", "NewVs", "服务器地址读取错误。", temp2, 255, FileName);
                string NewVs = temp2.ToString();                WritePrivateProfileString("version", "Vs", NewVs, FileName);
                WritePrivateProfileString("version", "Flag", "1", FileName);
                if (MessageBox.Show("升级已完成，重新进入订单系统？","提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Asterisk)
                == DialogResult.OK)
                {
                    CopyFile(downpath , System.Windows.Forms.Application.StartupPath );
                }
            }
        }        private void Form1_Load(object sender, EventArgs e)
        {
           // timer1.Enabled = true;
            StringBuilder temp2 = new StringBuilder(255);            GetPrivateProfileString("version", "Vs", "服务器地址读取错误。", temp2, 255, FileName);
            string ver = temp2.ToString();
            GetPrivateProfileString("version", "NewVs", "服务器地址读取错误。", temp2, 255, FileName);
            string NewVs = temp2.ToString();
            GetPrivateProfileString("version", "Flag", "服务器地址读取错误。", temp2, 255, FileName);
            string Flag = temp2.ToString();            this.label2.Text = ver;
            this.label4.Text = NewVs;
            if (label2.Text == label4.Text)
            {
                timer1.Enabled = false;
            }
            else 
            {
                timer1.Enabled = true;
            }
        }        private void CopyFile(string StartPath, string EndPath)
        {
            System.IO.File.Delete(EndPath);            FileStream fs = new FileStream(StartPath, FileMode.Open);
            //定义内存缓冲区
            byte[] buffer = new byte[(int)fs.Length];
            //将文件读入到内存缓冲区中
            fs.Read(buffer, 0, buffer.Length);
            fs.Close();            //定义一个文件流,用于将缓冲区中的文件流写入文件
            FileStream fs1 = new FileStream(EndPath, FileMode.Open);
            //写入文件
            fs1.Write(buffer, 0, buffer.Length);
            fs1.Close();
        }        private void timer1_Tick(object sender, EventArgs e)
        {
            StringBuilder temp2 = new StringBuilder(255);            GetPrivateProfileString("version", "Vs", "服务器地址读取错误。", temp2, 255, FileName);
            string ver = temp2.ToString();
            GetPrivateProfileString("version", "NewVs", "服务器地址读取错误。", temp2, 255, FileName);
            string NewVs = temp2.ToString();
            GetPrivateProfileString("version", "Flag", "服务器地址读取错误。", temp2, 255, FileName);
            string Flag = temp2.ToString();            label2.Text = ver.ToString();
            label4.Text = NewVs.ToString();
            UDTimes = UDTimes + 1;            if (label2.Text == label4.Text)
            {
                timer1.Enabled = false;
            }
            else 
            {
                progressBar1.Visible = true;                Down();
                
                StringBuilder temp = new StringBuilder(255);
                GetPrivateProfileString("version", "NewVs", "服务器地址读取错误。", temp2, 255, FileName);
                string NewVs1 = temp2.ToString();                WritePrivateProfileString("version", "Vs", NewVs1, FileName);
                WritePrivateProfileString("version", "Flag", "1", FileName);            }
        }
        //down方法：
        private void Down() 
        {
            FtpDown ftp = new FtpDown();
            
            string last = "";            string[] name = new string[] { };            name = ftp.GetFileList();            for (int i = 0; i < name.Length; i++)
            {
                if (name[i].ToString().StartsWith("Client_CT"))
                {
                    string FileName1 =  name[i].ToString();                    if (System.IO.File.Exists(downpath + "\\" + name[i].ToString()))
                    {
                        System.IO.File.Delete(downpath + "\\" + name[i].ToString());
                    }
                    ftp.Download(downpath, FileName1,progressBar1, out last);                }
            }
            
            ftp.CloseFtp();
            
            //ftp.Dispose();            //ftp.Close();
            
            
            Thread.Sleep(1000);
            
        }        private void timer2_Tick(object sender, EventArgs e)
        {
            //if (System.IO.File.Exists(downpath + "\\Client_CT.exe")) 
            //{            //    timer2.Enabled = false;
                
                
            //    if (MessageBox.Show("升级已完成，重新进入订单系统？", "提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Asterisk)
            //    == DialogResult.OK)
            //    {
            //        CopyFile(downpath + "\\Client_CT", System.Windows.Forms.Application.StartupPath + "\\Client_CT");
            //    }
            //    progressBar1.Visible = false;
            //}
        }    }
}